This invention relates generally to valves, and, more specifically to pin valves.
Pin valves have been in existence for a quite some time and have been used for a multiplicity of purposes. Within the last 15 to 20 years pin valves have been adapted to be used in gas powered guns suitable for projecting paint balls. These type of guns have become popular for use in simulated combat games. Pin valves are an important component of these guns because they provide a removable connection between the gun and a high pressure gas source such as a CO2 tank. The pin valve enables the CO2 tank to be easily detached from the gun when the gun is not in use or when the CO2 tank requires recharging.
As shown in FIG. 1, a prior art pin valve typically comprises a substantially cylindrical valve body having a first open end, a second open end, and an internal valve chamber in flow through connection with the first open end and the second open end. In a typical application, the first open end of the valve is connected to a paint ball gun, while the second open end is connected to a CO2 tank. A valve stem assembly is disposed within the internal valve chamber. The valve stem assembly in a prior art pin valve may be accessed and removed only through an access opening in the second open end of the valve body. The valve stem protrudes through a valve stem opening in the first open end of the valve body. The valve stem moves between a retracted position where the valve is open and an extended position where the valve is closed. The valve stem is biased toward the extended position such that the valve stem protrudes through the valve stem opening in the valve body and a O-ring seal surrounding the valve stem is in sealing contact with a valve seat located on the inner surface of the internal valve chamber proximal to the first open end of the valve body. The pin valve is opened when the valve stem is depressed and moved to the retracted position such as by being connected to a paint ball gun at the first open end of the pin valve.
The first open end of the pin valve is typically disconnected from the paint ball gun when the gun is not in use. The valve stem is in the extended position and the valve is closed when the first open end is disconnected. Unfortunately, when the first open end of the pin valve is disconnected from the paint ball gun it becomes exposed and is easily dented or otherwise damaged. If the first open end of the valve is dented, for example by hitting a solid object such as a concrete curb or a truck bed wall, it can result in damage to the valve stem or the inability to form an air-tight seal at this perimeter of the valve. The result is a pin valve that leaks.
Also, valve stems sometimes leak because of a poor seal between the O-ring and the valve seat. This problem frequently arises because of the difficulty in forming a proper valve seat surface during the manufacture of prior art pin valves. In order to have a valve that does not leak, it is vital that the surface of the valve seat is machined properly so that the valve seat has a sufficiently smooth and contiguous surface. Unfortunately, the valve seat surface is difficult to access in a prior art pin valve because it is disposed within the internal valve chamber at the opposite end of the cylindrical valve body from the access opening. The result is that many valve seat surfaces are imprecisely machined and a undue number of new valves need to be discarded prematurely because they leak.
A problem with prior art valves is that they are not amenable to being repaired. In fact, the valves currently used in paint ball guns are one of the most commonly replaced parts of the paint ball gun because they are not easily repaired. A particular problem is that replacement of the valve stem is difficult and time consuming. As shown in the prior art valve in FIG. 1, the valve stem assembly must be removed and replaced from the access opening in the second open end of the valve body. This requires that the entire valve be disconnected from the CO2 tank. Disconnecting the second open end of the valve is difficult because the threaded connection is typically fixed to the CO2 tank by the application of a special sealant material. The sealant acts to physically secure the connection between the valve and the CO2 tank and to prevent leaks at this junction. This sealant can be difficult to properly apply, and is even more difficult to remove when disconnecting the valve. Breaking this seal usually requires that the connection between the valve and the CO2 tank be heated to loosen the previously applied sealant. When a valve is reconnected it is important that the sealant material be properly applied because the connection may otherwise leak or pose a safety hazard. However, the sealant material may not be readily available when the valve needs to be replaced. Moreover, application of the sealant material entails a requisite level of skill not possessed by many persons owning or servicing the gun. Improper application of the sealant material, or failure to use the sealant material, can result in a safety hazard because the back end of the valve may become unscrewed when disconnecting the first end of the valve.
A further problem with prior art valves is that damage to the face of the first end typically requires that the entire valve be replaced. As shown in the prior art valve illustrated in FIG. 1, the face of the first end where the valve stem protrudes is integral with the first end of the valve body. When this face is dented the valve must often be replaced in its entirety rather than being repaired because the face is integral with the valve body. Needless to say, replacement of the entire pin valve is this is not a cost effective approach to maintaining the valve in proper working condition.
There is therefore a need for a valve which is easier to manufacture, easier to repair, and allows the valve stem assembly to be replaced directly from the first open end of the valve body.
The invention satisfies this need. The invention is an improved valve which is more easily repaired, and which is suitable for being used in a gas propelled paint ball gun for connecting the gun to a pressurized gas source.
The invention comprises:
(a) a valve body having first and second open ends;
(b) a valve body cover reversibly attached to the first end of the valve body, the valve body and the valve body cover cooperating to define an internal valve chamber, the valve body cover having an external face, an internal face and a valve stem opening, the internal face of the valve body cover comprising a valve seat; and
(c) a valve stem assembly disposed within the valve chamber, the valve stem assembly comprising a valve stem body, a valve stem attached to the valve stem body and a valve stem seal, the valve stem being movable between a retracted valve stem position and an extended valve stem position and being biased toward the extended valve stem position, the valve stem assembly being disposed within the valve chamber such that, (i) when the valve stem is in the extended valve stem position, the valve stem protrudes through the valve stem opening in the valve body cover and the valve stem seal is in sealing contact with the valve seat so as to seal closed the valve stem opening, and (ii) when the valve stem is in the retracted valve stem position, the valve stem seal is spaced apart from the valve seat sufficient so that the valve stem opening is not sealed closed.
The detachable valve body cover at the first open end of the valve body enables the valve stem assembly to be replaced directly from the first open end of the valve body, and thus virtually eliminates the need to disconnect the valve at the second open end. The valve seat surface is readily machined to form a smooth surface because it is disposed on the inner surface of the separately machined valve body cover. In a preferred embodiment, the removable valve body cover protects the first open end of the valve body and can be replaced independently if damaged. The removal of the valve body cover is simplified by designing the external face of the valve body cover such that it accommodates an allen wrench type tool.